simple methods for do-it-yourself monitoring of ... · 12/18/2014 steven j. thomson usda ars...
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Simple methods for do-it-yourself monitoring of temperature inversions and atmospheric stability
Steven J. Thomson, Daniel K. Fisher, Bradley K. Fritz1
Yanbo Huang, Reginald Fletcher
USDA ARS CPRSU, Stoneville MS1USDA ARS APMRU, College Station, TX
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
l Spraying must not occur where a temperature inversion prevents the spray cloud settling within the treated area.
l Temperature inversions are associated with STABLE atmospheric conditions.
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
8’ 27°F16’ 29°F32’ 31°F64’ 32°F
105’ 33°F
Surface Inversion - STABLE CONDITIONS
NOT OK to SPRAY!
Source: Ramsey (2001) http://www.cdpr.ca.gov/docs/enforce/drftinit/confs/2001/ramsey.ppt
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
Stability Ratiol Is a function of temperature at two heights and
wind speed.
l When temperature increases with height and this is combined with low enough wind speed, the stability ratio may indicate STABLE atmosphere.
l Application should not be made under these conditions.
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
Use 8 and 30 feet for temperature sensors; 15 feet for wind sensor
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
Atmospheric Stability Category
SR Result
UnstableNeutralStable
Very Stable
-1.7 to -0.1-0.1 to 0.10.1 to 1.21.2 to 4.9
OK to spray
-5
0
5
10
15
20
25
30
35
40
0:00
1:00
2:00
3:00
4:00
5:00
6:00
7:00
8:00
9:00
10:0
011
:00
12:0
013
:00
14:0
015
:00
16:0
017
:00
18:0
019
:00
20:0
021
:00
22:0
023
:00
Time of Day
0
50
100
150
200
250
300
350
Temperature at 15 ft (C)
Temperature at 30 ft (C)
Wind speed at 15 ft (miles/h)
Stabil ity ratio
Wind direction (degree)
Typical response from instruments on a tall tower
8
l We wanted portability since field surface conditions influence the rate of ground heating.
l We used a portable tower at first.l These were OK, but they were not as easy to set up
and move as first thought.
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
Soil texture also affects rapidity of soil warming.
New System
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
Large Helium Balloon.
Precision temperature sensors at 8 and 30 ft
Kestrel 4500 Bluetooth wind loggerat eye level.12/18/2014
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
Some temperature sensing systems
Bluetooth Radio
l We are still defining how much faster bare soil surface warms compared with a crop canopy.
l Final form of recommendations will be referenced to sunrise and sunset.
l What about conditions early in the season?l Data shows that we lose up to one hour in the morning and one
hour at night when it is acceptable to spray, shortening the time window.
l Cloud cover appears to have the same effect.l Wind effects are being considered in recommendations.
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
Recommendations to applicators
l Data can be obtained at the field level using a Windows-based tablet (via Bluetooth).
l Web-based or Android/Iphone app for pilot and farm manager using easily obtainable measurements (like use of temperature differences – recommendations from Arkansas Plant Board): http://170.94.200.136/weather/Inversion.aspx.
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
l We are working on a web interface to monitor sensors remotely and present recommendations
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
12/18/2014 Steven J. Thomson USDA ARS Stoneville MS
Thank You!
l Contact: [email protected]
Work partially funded by a grant from the Mississippi Soybean Promotion Board (MSPB)